During the control of various processes in industry, for example during the control and/or regulation of a cooling line downstream of a hot strip mill train, the problem arises that, as a rule, measurements can be made only at the input of the line and at the end of the line, but that no intermediate measuring stations are possible. Such lines can, however, be very long—for example being the cooling line of a hot strip mill train in the case of which the hot rolled strip has to be sprayed with cooling water over a relatively long length and be cooled thereby. Consequently, the problem arises that the measured values measured at the end of the cooling line can be converted only with a large dead time into regulated variables for regulation of the line, and that there are available for the control elements distributed over the line only the regulated variables calculated on the basis of the values measured at the start and at the end of the line, but no intermediate values.